1. Field of the Invention
The present invention relates to a device for detecting an obstacle, the device being mounted on an automotive vehicle, and especially to an on-board device for detecting a motorcycle and/or a bicycle passing by the automotive vehicle.
2. Description of Related Art
An example of a device having an illuminating device for illuminating objects by an automotive vehicle, such as a motorcycle passing-by, is shown in JP-A-2005-41398. The illuminating device is controlled according to detection results of ultrasonic sensors mounted on the vehicle. It is difficult for the ultrasonic sensors having a detection distance of about 1 meter to detect all of motorcycles passing by an automotive vehicle because some of the motorcycles pass by the vehicle with a distance more than 1 meter apart from the vehicle. It is also difficult to stably detect a motorcycle passing by at a high speed relative to a driving speed of the automotive vehicle, because the ultrasonic sensors are usually set to detect an object having a low relative speed.